Technical Popularization Pamphlet

TPP 5www.craim.ca

VisionCRAIM aims to be the benchmark in hazardous substance risk managementwithin the scope of sustainable development by applying rigorous, responsibleand concerted methodologies.

MissionTO DEVELOP rigorous tools and methods that provide responsiblemanagement of risks related to hazardous substances. TO PROMOTE and support a culture of collaboration between allstakeholders to effectively manage the risks involving hazardoussubstances.TO FOSTER, with stakeholders, a reduction in the risks of major industrialaccidents through the implementation of appropriate prevention,preparedness, response and recovery measures.

Vision and Mission of the CRAIM

This document, based on current available facts, is designed to familiarize the readerwith certain basic concepts. The reader must be aware that the information provided inthis document is not complete, and therefore, that other complementary sources mustbe consulted to avoid any unfortunate situations. The reader is entirely responsible forany decisions or actions taken on the basis of this document.

5

LPGLNG

2thEDITION

Emergency Response

1. Situation analysisa. Initial steps Establish a safety perimeter: evacuate within a radius of 1600m in case of fire and 800m in case of an important spillVerify the condition and the behavior of the reservoir or tankDetermine if the situation is stable or deterioratingIdentify the local dangers and risks, quantities involved and number of affected people.Determine the required resources for an appropriate response. b. Evaluate the product behaviorEstimate the leak or spill flowrateObtain weather conditions (Wind speed and direction, temperature, humidity)Identify more accurately the likely affected areasModify, if necessary, the security perimeter based on evaluation results.c. Personal protectionWear fireproof clothing and low temperature resistance fabricWear a self-contained breathing apparatus when approaching the spill source (danger of asphyxia). d. Detection equipmentUse combustible gas indicatorEnsure proper calibration of indicator.

2. Possible response strategiesNever respond alone, approach with the wind at your backStop or plug leak if possiblePromote cloud dispersion using streams of waterNever spray a LNG pool directly (Possible RPT and ensuing overpressure)A LPG cloud will infiltrate underground infrastructures (LPG is denser than air)Prevent the flow of liquid LNG into sewer systemsPrevent the inflow of LPG or LNG vapors into buildingsVerify the presence of combustible gases in the sewers, underground structures and buildings (any confined spaces in proximity)Do not extinguish a fire before interrupting the combustible source (danger of reflash (re-kindle) and flash fire)Cool adjacent structures in case of a fireIf there is a risk of a BLEVE, evacuate the surrounding area and let the tank content burnout.

For additional information, please consult the following documents:

LPG:API Standard 2510: Design and Construction of LPG InstallationsAPI Publication 2510A: Fire-Protection Considerations for the Design and Operation of LiquefiedPetroleum Gas (LPG) Storage FacilitiesCCPS Guidelines for Evaluating the Characteristics of Vapour Cloud Explosions, Flash Fires & BLEVEs,Center for Chemical Process Safety

LNG:CSA Z276, Liquefied natural gas (LNG) - Production, Storage, and Handling

and

(Liquefied Petroleum Gas)

(Liquefied Natural Gas)

* Conseil pour la réduction des accidents industriels majeurs

*

www.craim.ca

11 2

3 4

**RPT: Rapid Phase Transition: A significant temperature difference between LNG and awarmer liquid (e.g. water) can instigate, under certain conditions, the “quasi–instant”vaporization of LNG. The sudden increase in volume (liquid to vapor) can generate a shockwave. This accidental phenomenon can be referred to as a “Cold explosion” (Sudden generationof overpressure, without combustion)

***BLEVE (Boiling Liquid Expanding Vapor Explosion). Specific situation related to LPG storage vessels. Can be caused by one of the following:

• Thermal aggression (most common)

• Mechanical impact

• Overfilling coupled with metal (tank) weakness

Figure illustrating the BLEVE phenomenon:

Introduction

Safety BarriersPREVENTION BARRIERSa. Regular maintenance programb. Personnel trainingc. Building Codesd. Electrical Classificatione. Combustible Gas detection systems

with alarmsf. Automatic shutoff valvesg. Land useh. Installing tanks far from buildings

or flammable materiali. Anti-intrusion fencesj. Cameras

PROTECTION BARRIERSa. Safety wallb. Dikesc. Sprinklers, water curtaind. Fixed Fire Nozzlese. Firefighting foam for LNGf. Firefighting exercisesg. Evacuation proceduresh. Emergency plani. Fencingj. Land use

For more information on safety barriers, please consult the TPP #3 or the CRAIM Guide (2007), chapter 4.

TANK

VaporOverheatingPressure buildup

Heat Source

Fire Ball

Heat lossConvection

Tank rupture and suddenrelease of content

Liquefied Gas

Vapor

Liquefied Gas

Vapor

Liquefied Gas

TANK

Vapor

Liquefied Gas

LNG(methane)

Produces a vapor cloud that remains on the grounduntil the cloud temperature reaches -100°C, it thenrises. A liquid discharge creates a pool of liquid thatspills towards the lowest points on the ground.

LPG (propane)

Produces a vapor cloud that remains on theground, given that propane is heavier than air.Propane can create a pool of liquid undertemperature below -42°C.

Initiating Event

BLEVE***GAS release

Explosion*

Liquid spill

Spreading -Vaporization

Atmospheric dispersion

Ignition source

Flash Fire Jet Fire

Pool Fire

RPT** Fire Ball

Ignition source

two-phase flow release

Accident scenarios:

Main physical properties:

Outflow behavior:

* Explosions of Natural Gas in open air are highly unlikely and require confinement of the gas or the acceleration ofthe flame front with the presence of obstacles. (Margan and Hill, 1997)

* All liquids never really ignite. It is the vapors, on the liquids surface, that are combustible. (Combustion, requires oxygen, which is not readily available in liquids)

Properties

UN number

Color, odor

Specific gravity of liquid

Specific gravity of gas

Boiling Point (°C)Auto-ignition temperature (°C)

Flammability Limit Gas

Flammability Liquid *

Water solubility

LPG (propane)

1075 or 1978

Clear, odorized with mercaptans

0.51 to 0.58

1.5

- 42

470

2.2 à 9.5%

flammable

75 mg/l

LNG (methane)

1972

Clear, odorless

0.42 to 0.5

0.6

- 161

595

5 à 15%

flammable

26 mg/l

GREEN BOXE:LNG accidents only

YELLOW BOXES: LPG accidents only

LPG and LNG are hydrocarbons mainly used as fuel for heating. LPG comprises propane and butane.LNG is essentially liquefied methane. LPG and LNG are stored and transported in a liquefied state inorder to reduce their volume. LPG's are liquefied under pressure at ambient temperature, whereasLNG is cryogenically liquefied (using cold temperature) at atmospheric pressure.

TPP 5